Hydraulic brake system



R. vl-lox-YsTl-:TTER

HYDRAULIC BRAKE SYSTEM sept. zo, -193s.

Filed March 16, 1934 *q In.

lll

Patented Sept.' 20, 193s l 7 Y I.

UNITED 'STATES PATENT GFFICE" HYDRAULIC BRAKE SYSTEM nchen nofstetter, Jackson, Mich. Application March v16, 1934, Serial No. 715,846

2 claims. (ci. sos-.sh

'Ihel present invention relates to improvements' Fig. 1 a suitable casting Ill constitutes a master in the hydraulic brake system for automotive vereservoir Il for the operating uid. A master `hicles, and the like. cylinder I2 is provided centrally of the casting I@ I In hydraulic brake systems in use at the present and at' one end of which a piston I3 is received 5 time frequently line failures occur between the for longitudinal reciprocation. Located withn 5 cylinder directly associated with the brake shoe the piston I3 for limited relative movement relavand the master cylinder. When this happens the ltive thereto is provided a hollow valve I4. As entire system is rendered useless. shown, a springk seat I5 is associated with the Thus one of the objects ofthe present inventionv valve It with which the spring I6 abuts toconm is to provide a system which overcomes the above tinuously urge the valve It and the piston I3 to Al0 stated condition and which greatly' increases the the right, as viewed in Fig. l. The valve It is factor of safety of the vehicle by assuring the closed at the right and with the left end opening proper operation of, at least, two brakes in the into the cylinder I2 forward of the piston I3. 'A lconveriientyfour wheelbrake system, upon line port Il is located in the valve Id which comfailure. n p municates with the reservoir H through a pasl5 Another object is'to provide simple, inexpensive sage I8 opening into a space I9, located at the and eifective means for assuring a proper supply rear of the piston I3. of operating fluid` tol the braking system at all Ports 2li are provided which communicate with times as Well as providing for expansion and conthe auxiliary cylinders 2| which are two in numtraction of the uid under temperature changes. ber in the embodiment illustrated. Pistons 22 20 A further object is to provide a simple and .are received within the cylinders 24 for longitudieffective mechanical booster for brake application' nal reciprocation. These pistons, as shown, have which is under the direct control of the manually longitudinally spaced cylinder engaging portions operated v,braise pedal and which does not affect which approximate the diameter of the cylinders 25 the manual operation of the braking system, if 2l for guiding purposes with the major extent of desired, or should lt become necessary upon failthe pistons, preferably of substantially less diamure of-the mechanical booster. eter than the, cylinders 2|. With such a con Other objects and advantages of the invention struction the pistons 22 will reciprocate without residing in the combination and construction and binding and aS the area 0f the DSODS 22 in actual arrangement of parts will become apparent from sliding contactwith the walls of the cylinders 2l 30 the following description when considered in conis not greet e suioient amount of oil is permitted nection with the accompanying drawing. The to seep pest the pistons 22 to compensate for any invention is clearly defined in the claims. slight leakage, in the system. In order to take In the drawing wherein there are illustrated, care of expansion due to temperature changes by way of' example, several of the innumerable Check Valves 23 are Preferably 100M/ed in the PS 35 forms which the present invention may take, tOnS to enable the Operating fluid to flow back Fig. l is a longitudinal cross sectional view into the reservoir il. Springs 24 continuously through the master cylinder, reservoir and meurge the piston tothe left as viewed in Fig. 3. chanical booster showing the association with the Upon the directing 0f fluid pressure against the 40 brake pedal, left end of the pistons 22,the fluid located for- 4o Fig. 2 is a fragmentary end view taken from ward of the right ends cfthe pistons is forced out ,the left of Fig, 1, through the outlets 25 which are coupled to the Fig. 3 is a cross sectional view taken upon line lines (not ShOWn) extending t0 the Operating Cy1.

3--3 of Fig. 2 `through the master'and auxiliary nder located upon the wheel brake of the front cylinders, l y and rear wheels, for example. Upon failure of 4f Fig, 4 is a fragmentary longitudinal cross Seceither line connected to the auxiliary cylinders tional viewof a modmed form of mechanical- 2I. the release of pressure forward of the piston booster, f will result in the piston 22 being urged to the Fig. 5 is an enlarged fragmentary cross secright and the'ClOSing of the inner end- 26 of the tional view of a modified auxiliary cylinder showoutlet 25 by the forward end of the piston 22 to 50 ing valve mechanism for sealing a line upon failavoid further loss of the operating fluid from the ure or rupture thereof, and reservo i" I E Fig. 6 is a fragmentary view taken on line 6-6 It should become .apparent from the foregoing of Fig. 5 showing the washer construction. descripticnthat by coupling the front wheel brake Having specific reference to the drawing in cylinders with the `fline communicating with one do of the auxiliary cylinders and the rear Wheel stood that the present arrangement possesses the within` the system a longitudinally `slidable rod- 'l is provided which may be actuated by the usual same equalizing characteristics of the systems now in use.

For creating the necessary operating pressure brake pedal, a mechanical booster or both as will be hereinafter described. This rod is closely tted within the hole 2i which constitutes a guide therefor. Initial movement of the rod 2li to the left from the position shown in Fig. 1 will result in the valve lil being moved to the left relative to the piston i3. Such movement by the rod 2l and valve ld Will result in the closing of the port Il by the guiding wall of the piston i3. Further movement of the rod 2l will bring the same into abutment with the piston i3 which will then be urged to the left to create the necessary additional operating pressure in the system.

As illustrated in Fig. 1 a cylinder 28 is located at the Vright end of the casting it in axial alignment with the cylinder l2. A piston Z9 is received with this cylinder for reciprocation through which the rod 2l extends. The piston 29 may be either I'lxedly secured to the rod 2l or slidable thereupon. Preferably an annular shoulder 30 is provided upon the rod 2l against which the piston abuts when urged to the left, to mechanically operate the brakes. The shoulder 3u also acts to return the piston to the position shown in Fig. 1. With the piston 29 slidably received upon the rod 2l, manual actuation of the rod is vfacilitated as it is not necessary to traverse the piston throughout'the length of the cylinder 28. The end of the cylinder 28 is closed by a casting Si having a bore 32 through which the rod 2l extends. Within the casting 3i is disposed and housed the necessary ports and valve mechanism for directing' the iiuid pressure against the piston 29 to mechanically apply the brakes. In my preferred form, oil, or other suitable uid, under pressure is admitted through the inlet 33 and is directed into the cylinder 28 against the piston 29 through the passages Sil-35. An outlet 36, which would be connected with the crank case when the pressure oiling system of the vehicle is employed as a source of operating power, is in communication with the passage 35. Such communication is interrupted or constricted by a valve 31 Which is lightly urged to a seat by the l spring 38 with the brake pedal 39 inthe manner shown. The stern 40 of the valve 31 is axially slidable relative in its carriage received for reciprocation in a bore 42 of the casting 3l. It

vis to be understood that the slot of the lost motion linkage 52 is-so designed and its relation so corelated'with reference to the strength of the spring 38 that the luid pressure built up behind the piston 29 always opens the Valve 3l before the piston 29 has moved sumciently to take up the lost motion and thus avoid urging the link i to the left under full pressure. This carriage is reciprocated through the linkage connected to the brake pedal consisting of a rod 43 having one lend connected to the carriage di and the other end slidably received within the tubular link till. The link lill is enlarged at 45 to house the spring d6 which acts against an annular shoulder l1 upon'the rodll to urge the rod i3 to the position arcaico Atothe brake pedal in any suitable way, is shown as attached at te to an arm it which is rocked about the shaft il as a unit with the brake pedal. At the upper end oi the arm ci) a horizontal link 5i is provided which has a lost motion connection with the rod 2li as at 52.

In operation, with the brake pedal in the posil tion shown with the brakes released, fluid under pressure will :dow through the inlet hence into the passage 35 filling the space back of the piston 29. Because of the light compression of the spring 35, the pressure of the fluid will force the valve 3l .from its seat and owout through the outlet @t without building up suflicient pressure to move the piston 29 to the left. When the brake pedal is depressed thecarriage il will be moved to the left gradually increasing the compression of the spring 38 to urge the valve 3l toward a seat to gradually decrease the flow of fluid through the outlet 3G. The result is the gradually building up of pressure back of the piston 29 to move the same to the left to eiect a smooth, uniform ap,

plication of the brakes. Additional movement of the link dil after the valve 3l has been fully seated will result in the compression of the spring Alt which, it is to be understood is considerably stiller than the spring 38. In the event of failure of the mechanical booster or desire to manually operate the brakes, the rod 21 is moved to the leftthrough the lost motion linkage 52; the link 5l being capable of only a limited movement without actuating the rod 2li; (not shown) return the brake pedal and the assoclated mechanism to the position shown in Fig. 1 after manipulation. Conduit. 53 communicating with the outlet 36 drains into the crankcase any of the operating fluid which may pass the piston 29. the outlet 35, drains any accumulation of operating uid which may pass the rod 2l and carriage di.

In Fig. 4 is shown a modified embodiment of Conventional means A conduit 5G, likewise communicating with my mechanical booster in which an inlet 55 communicates with the cylinder 28 through a bore varrangement will result in a smooth, gradual actuation of the brake mechanism.

Referring to Fig. 5, a modiiled auxiliary cylinder structure is shown in which the travel of the piston to the extreme right upon decrease in pressure upon the forward end of the piston, as would take place upon line failure, closes a check valve to avoid loss of operating-huid. As illus;- trated the piston 59 carries a plunger t0 which extends beyond the forward end of thefpiston. A ball valve 6i is located within the chamber t2 which communicates with the outlet t3 leading to the Wheel brake cylinder. A spring stressed plunger 56 urges the ball valve 6i to a seat against the washer t5 which has a serrated edge t6 to permit the operating fluid to ow past the ball valve through the channels 6l into the chamber t2 and hence to the outlet 63. Upon line failure the piston te will be urged to the extreme right of the auxiliary cylinder by the pressure in plunger 60 forces the ball valve to the dotted .anonce l line position closingthe outlet. The valve iv in this position will` be held to a. seat bythe plunger M. After repair has been made it becomes necessary to manually force the ball valve 'to the position shown in Fig. 5. 'K From theu i'oregoing description it should become apparent to those versed in th'e art that the present invention consists of three major fea.-` tures all of which may be advantageouslyvempioyed in combinations and arrangements other than those shown. At the same time I have comhined all? these features i'nto a compact unitary "commercial structure, which may be inexpem,"

voutletupon reduction of fluid pressure in the sively constructed, which provides a factor of safety not heretofore obtained, and which re suits in smooth. uniform actuation, at all times,

i ous changes and modications as will readily suggest themselves and fall within the scope of theappended claims. y

NHaving described my invention what I claim as new and desire to-protect by Letters Patent is:

1. In ahydraulic brake system. a mastercylinder, a plurality of auxiliary cylinders having communication with said master cylinder, out

llets associated Vwith each of said auxiliary cylinders, pistons located in said master and auxiliary cylinders. means acting upon said master piston to direct uuid under pressure against one end of said auxiliary pistons to move the same ln one direction to build up uid'pressure, valves located in said outlets and means' associated with said pistons for actuating said valves to close said outlet end of said auxiliary cylinders.

2. In a hydraulic brake system. an auxiliary cylinder, an outlet from said cylinder, a piston located in said cylinder, means directing fluid under pressure against said piston to move the same in a direction to build up pressure in said cylinder, a valve in said outlet, and means con- "nected to said piston for actuating` said valve to close said outletv upon a reduction'of pressure .in said auxiliary cylinder.

ROBERT HOFSTEITER. 

